Testing system that determines contact erosion in circuit breaker

ABSTRACT

A testing system includes a truck carrying a circuit breaker, a fixed contact, and an actuator piston connected to a movable contact. A test platform supports the truck in a contact testing position and includes a sensor circuit mounted on the test platform and positioned under the truck and aligned with the circuit breaker when the truck is on the test platform in the contact testing position. The sensor circuit is configured to acquire displacement data of the actuator piston when the movable electrical contact is moved between the open and closed positions. A controller is coupled to the sensor circuit and configured to receive the displacement data and determine electrical contact erosion within the circuit breaker.

FIELD OF THE INVENTION

The present invention relates to the field of electrical systems, andmore particularly, this invention relates to electrical switchgearsystems having circuit breakers.

BACKGROUND OF THE INVENTION

Metal-clad or metal-enclosed medium voltage switchgear systems operateas three-phase systems that connect to the three-phase powerdistribution grid and provide various control functions and provideprotection against short circuit events and similar overcurrent or otherfault conditions. The switchgear systems may include transformers toreduce the primary circuit voltage, which can be greater than 1,000volts, to a much lower voltage that may energize control circuits ormonitor or meter the primary voltage. The switchgear systems andassociated load currents may be protected from damage by a fuse when thetransformers fail. Switchgear systems may also incorporate circuitbreakers, which open and close individual circuits and may be mounted ona truck, which may be racked in and out of a switchgear housing via aracking system. The circuit breakers may be connected and disconnectednot only from primary circuits, but also may be connected anddisconnected from a secondary control power circuit. Short circuitevents and similar overcurrent or other fault conditions may generatevery large currents, which places physical stresses on the circuitbreakers and the racking system.

Switchgear circuit breakers may include vacuum interrupters that operateas switching devices, and include a fixed electrical contact positionedwithin a vacuum sealed breaker housing, and a movable electrical contactmounted for movement in the breaker housing. An actuator piston and adrive assembly may be coupled to the actuator piston and may have storedenergy, such that the contacts are normally closed, but are opened uponan electrical fault condition, such as a current overload, shortcircuit, or abnormal level voltage condition.

Usually, one vacuum interrupter as a circuit breaker is provided foreach phase of a multi-phase circuit such as a three-phase circuit, andthe several phases are actuated simultaneously by a common operatingmechanism, or in some cases separately. Over the life of each vacuuminterrupter, the contact surfaces may erode because of the arcing thatoccurs between the contacts during a circuit interruption. As a result,each contact may lose material over its life due to contact erosion. Forexample, it is possible that each contact may lose about 3 to 5millimeters (mm) of material in a system that has about 14 millimetersof contact movement. As a result, some of the compression that may beassociated with spring mechanisms as part of the vacuum interrupter maybe lost. The contact erosion may also create insufficient contact forcebetween the contacts, and thus, increase the risk of overheating orexplosion in the event of a short circuit and failure to interrupt thecircuit. There have been some proposals to monitor contact wear, such asadding optical or electronic measuring devices or mechanical gauges intothe vacuum interrupter itself, but often space is limited within thecircuit breaker, making it difficult to determine electrical contacterosion within a circuit breaker.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts that arefurther described below in the Detailed Description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

In general, a testing system for a circuit breaker may comprise a truckcarrying a circuit breaker, wherein the circuit breaker may comprise abreaker housing, a fixed electrical contact and a movable electricalcontact mounted within the breaker housing. The movable electricalcontact may be movable between an open and closed position relative tothe fixed electrical contact. An actuator piston may be connected to themovable electrical contact and extend downward from the breaker housingand may be configured to connect to a drive assembly that drives theactuator piston and moves the movable electrical contact between openand closed positions with the fixed electrical contact. A test platformmay be configured to support the truck carrying the circuit breaker in acontact testing position on the test platform, which may comprise asensor circuit mounted on the test platform and positioned under thetruck and aligned with the circuit breaker when the truck is on the testplatform in the contact testing position. The sensor circuit may beconfigured to acquire displacement data of the actuator piston when themovable electrical contact is moved between the open and closedpositions. A controller may be coupled to the sensor circuit andconfigured to receive the displacement data and determine electricalcontact erosion within the circuit breaker.

The sensor circuit may comprise a first laser configured to emit a firstoptical beam onto a surface of the actuator piston, and a first opticalsensor that receives reflected light from the surface of the actuatorpiston. The sensor circuit may comprise a second laser configured toemit a second optical beam onto a surface of the breaker housing, and asecond optical sensor that may receive reflected light from the surfaceof the breaker housing. The controller may be configured to determineactual electrical contact erosion based upon displacement of theactuator piston and breaker housing. The controller may be configured torecalibrate the position of the fixed and movable electrical contactsbased upon the displacement data obtained from movement of the actuatorpiston and breaker housing. The truck may include a bottom panel havingorifices aligned with respective first and second lasers to allow thefirst and second optical beams from the first and second lasers to passupward through the bottom panel to respective surfaces of the actuatorpiston and breaker housing. The controller may be configured todetermine actual contact erosion by subtracting the displacement of thebreaker housing from the displacement of the actuator piston.

In an example, first, second and third circuit breakers may be carriedon the truck, and first, second and third sensor circuits may be mountedon the test platform underneath the truck and aligned with respectivefirst, second and third circuit breakers when the circuit breaker is inthe contact testing position on the test platform. The first, second andthird circuit breakers may be electrically connected in a three-phasecircuit breaker configuration. The movable electrical contact may beopened from the fixed electrical contact in response to an abnormalelectrical condition. The circuit breaker may include upper and lowerterminals configured to engage electrical connectors carried within aninterior compartment of a switchgear frame when the circuit breaker isin an electrically connected position. The actuator piston may comprisea spring and cylindrically configured actuator block engaging thespring. The breaker housing may comprise a vacuum chamber housing andthe fixed and movable electrical contacts are sealed within the vacuumchamber housing.

A method aspect of operating a testing system for a circuit breaker maycomprise positioning a truck carrying a circuit breaker into a contacttesting position on a test platform. The circuit breaker may comprise abreaker housing, a fixed electrical contact and a movable electricalcontact mounted within the breaker housing. The movable electricalcontact may be movable between an open and closed position relative tothe fixed electrical contact. An actuator piston may be connected to themovable electrical contact and extend downward from the breaker housing,and may be configured to connect to a drive assembly coupled to theactuator piston that drives the actuator piston and moves the movableelectrical contact between open and closed positions with the fixedelectrical contact. The method includes acquiring displacement data ofthe actuator piston when the movable electrical contact is moved betweenthe open and closed positions using a sensor circuit mounted on the testplatform and positioned under the truck and aligned with the circuitbreaker when the truck is in the contact testing position, and receivingthe displacement data within a controller coupled to the sensor circuitand determining electrical contact erosion within the circuit breaker.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome apparent from the Detailed Description of the invention whichfollows, when considered in light of the accompanying drawings in which:

FIG. 1 is an isometric view of an example electrical switchgear system,in accordance with a non-limiting example.

FIG. 2 is a schematic isometric view of a truck carrying a circuitbreaker and showing a sensor circuit positioned under the truck inaccordance with a non-limiting example.

FIG. 3 is a schematic plan view of a sensor circuit and first, secondand third sensor circuits that may be mounted under the truck within theswitchgear frame, or on a test platform.

FIG. 4 is a sectional side elevation view of the circuit breaker anddrive mechanism showing in section the sensor circuit in a contacttesting position in accordance with a non-limiting example.

FIG. 5 is a partial side sectional view of the truck carrying thecircuit breaker and showing the sensor circuit on the switchgear frameunder the truck and aligned with the circuit breaker in a contacttesting position.

FIG. 6 is a side sectional view similar to that of FIG. 5 , but showingthe truck on a testing platform having a sensor circuit.

FIG. 7 is an isometric view of the underside of a circuit breaker andshowing locations where first and second optical beams may be reflectedfrom the actuator piston and breaker housing.

FIG. 8 is a flowchart showing a method of operating a switchgear systemfor determining electrical contact erosion within the circuit breakerusing the switchgear system such as shown in FIG. 4 .

FIG. 9 is a high level flowchart of a method of operating a testingsystem for a circuit breaker using the test platform such as shown inFIG. 6 .

DETAILED DESCRIPTION

Different embodiments will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsare shown. Many different forms can be set forth and describedembodiments should not be construed as limited to the embodiments setforth herein. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope to those skilled in the art.

Referring now to FIG. 1 , there is illustrated generally at 100 anelectrical switchgear system in accordance with a non-limiting examplethat includes a front switchgear section 102 having first and secondsets of front upper and lower switchgear housings 104, 106, 108, 110 andhaving joined sidewalls. A rear switchgear section 114 includes firstand second sets of rear upper and lower switchgear housings with threehousings 116, 120, 122 being illustrated, and having joined sidewallsand connected to the rear of the respective front upper and lowerswitchgear housings 104, 106, 108, 110.

Joined sidewalls of first and second sets of front upper and lowerswitchgear housings 104, 106, 108, 110, 116, 120, 122 include a steppedoffset section to form a ventilation duct 134 extending the height ofthe switchgear system 100. Each illustrated switchgear housing 104, 106,108, 110, 116, 120, 122 includes a switchgear frame 124 (FIGS. 2-4 )that defines an interior compartment 128 (FIG. 4 ).

It is possible that front and rear switchgear sections 102, 114 mayinclude “n” sets of both front and rear upper and lower switchgearhousings and form a series of switchgear housing sections forming theelectrical switchgear system 100. In an example, the left front upperswitchgear housing 104 may include within the interior compartment 128upper and lower compartments where each of the upper and lowercompartments may include the front opening defined at the front of theswitchgear housing 104 and a truck and drive mechanism. The front leftlower switchgear housing 106 in this example may include a circuitbreaker truck 150 and circuit breaker drive mechanism 152 such asexplained below in the more detail with reference to the description ofFIG. 4 .

The front switchgear section 102 upper and lower switchgear housings104, 106, 108, 110 and rear switchgear section 114 having the upper andillustrated lower switchgear housings 116, 120, 122 each may include oneor more interior compartments 128 (FIGS. 2, 4 and 5 ) and variouselectrical switchgear components. On the outside of the electricalswitchgear system 100, and more particularly, on the outer side of therear housings 120,122 as shown in FIG. 1 , there are shown componentsthat make up part of a main bus extension assembly and phased shortingbus 156 that may extend from a main bus compartment.

The rear switchgear section 114 may include in the various interiorcompartments of the illustrated switchgear housings 116, 120, 122 a mainbus assembly, a ground bus assembly interconnect, a potentialtransformer (PT) and control power transformer (CPT) jump bus assembly,a line bus assembly, a cable compartment, various bus bars and otherassociated electric components. The front section upper and lowerswitchgear housings 104, 106, 108, 110 include doors 104 a, 106 a, 108a, 110 a for each switchgear housing to permit access into each interiorcompartment 128.

Referring now to FIGS. 2-4 , the switchgear system 100 is illustrated ashaving a switchgear frame 124 with an interior compartment 128. Acircuit breaker truck 150 carries the circuit breaker 250 and issupported for movement on the switchgear frame 124 within the interiorcompartment 128 into a contact testing position, such as illustrated at160, where electrical contact erosion may be determined within thecircuit breaker. The circuit breaker 250 includes a breaker housing 164,which in this example is formed as a vacuum interrupter 270 (FIG. 4 ).

As best shown in FIG. 5 , the breaker housing 164 supports a fixedelectrical contact 168 and a movable electrical contact 170 are mountedwithin the breaker housing 164. The movable electrical contact 170 ismovable between an open and closed position relative to the fixedelectrical contact 168. An actuator piston 174 is connected to themovable electrical contact 170 and extends downward from the breakerhousing 164. A drive assembly 176 is coupled to the actuator piston 174and configured to drive the actuator piston and move the movableelectrical contact 170 between open and closed positions relative to thefixed electrical contact 168.

As best shown in FIG. 3 , a sensor circuit 180 is illustrated andincludes first, second and third sensor circuits 180 a, 180 b, 180 c,and is mounted on the switchgear frame 124 under the circuit breakertruck 150 and aligned with the circuit breaker 250 when in the contacttesting position 160 and configured to acquire displacement data of theactuator piston 174 when the movable electrical contact 170 is movedbetween the open and closed positions. A controller 226 is coupled tothe sensor circuit 180 and configured to receive the displacement dataand determine electrical contact erosion within the circuit breaker 250.

In an example, each sensor circuit 180 includes a first laser circuit182 having a first laser 184 that is configured to emit a first opticalbeam as light onto a surface of the actuator piston 174. The term“actuator piston” as used herein for purposes of receiving an opticalsignal includes those components that are directly or indirectlyconnected to the movable electrical contact 170 and operate together todrive or direct the movable electrical contact into and out ofengagement with the fixed electrical contact 170 and may be used fordetermining displacement of the actuator piston. Example components mayinclude an actuator spring 188 and for displacement purposes, acylindrically configured actuator block 190 engaging the actuator springas best shown in the sectional view of FIGS. 5 and 6 . The term“actuator piston” may also include any support plates or other supportmembers such as a transverse extending support plate 192 that includes acircular configured mounting member 194 as shown in the underside viewof the circuit breaker 250 of FIG. 7 . The transverse extending supportplate 192 and its circular configured mounting member 194 engage in thisexample the actuator block 190 and operate in conjunction with the driveassembly 176.

As shown in FIG. 7 , the transverse extending support plate 192 andcircular configured mounting member 194 are also connected to thethreaded end 196 of the actuator piston 174. A first optical sensor 198as a detector (D1) receives the reflected light that has been emitted asthe first optical beam from a reflective surface of the actuator piston174, which may be a surface such as the threaded end 196 of the actuatorpiston 174 or the actuator block 190, or part of the transverseextending support plate 192. The sensor circuit 180 further includes asecond laser circuit 200 having a second laser 202 configured to emit asecond optical beam onto a surface of the circuit breaker housing 164. Asecond optical sensor 204 as a detector (D2) receives the reflectedlight from the surface of the breaker housing 164 that had been emittedas the second optical beam from the second laser 202.

The controller 226 is configured to determine actual electrical contacterosion based upon the displacement of the actuator piston 174 andcircuit breaker housing 164. During an electrical short circuit or othersimilar abnormal electrical condition that is detected by components ofthe switchgear system 100, the drive assembly 176 coupled to theactuator piston 174 may aid in driving the actuator piston and move themovable electrical contact 170 into an open position relative to thefixed electrical contact 168. During that circuit breaker interrupt, notonly do the actuator piston 176 and associated components move, but alsothe circuit breaker housing 164 itself will move slightly in someexamples at a few millimeters, e.g., 1-3 millimeters and in a decreasingdamping or oscillation manner. Using the measured displacement of theactuator piston 174 and the circuit breaker housing 164, it is possiblefor the controller 226 to determine actual movement and thus contacterosion by subtracting the displacement of the breaker housing from thedisplacement of the actuator piston.

The controller 226 may also be configured to recalibrate the position ofthe fixed electrical contact 168 and movable electrical contact 170based upon the displacement data obtained from movement of the actuatorpiston 174 and breaker housing 164. In an example, the circuit breakertruck 150 may include a bottom panel 208 (FIG. 4 ) having orifices 210aligned with the respective first and second lasers 184,202 to allow therespective first and second optical beams emitted from the first andsecond lasers 184,202 to pass upward through the orifices 210 located inthe bottom panel 208 to respective surfaces of the actuator piston 174and breaker housing 164 and be reflected therefrom to determinedisplacement data.

As shown in FIG. 2 , first, second and third circuit breakers 250 a, 250b, 250 c are carried on the circuit breaker truck 150, and first, secondand third sensor circuits 180 a, 180 b, 180 c (FIG. 3 ) are mounted onthe switchgear frame 124 underneath the truck and aligned withrespective first, second and third circuit breakers when in the contacttesting position 160. As shown in the schematic diagram of FIG. 3 , asensor support bar 214 supports the first, second and third sensorcircuits 180 a, 180 b, 180 c, each having first and second lasers184,202 and the first and second optical sensors 198,204 as best shownin FIG. 4 showing a single sensor circuit. The first, second and thirdcircuit breakers 250 a, 250 b, 250 c are electrically connected in athree-phase circuit breaker configuration.

The drive assembly 176 that is connected to the actuator piston 174 maybe configured to open the movable electrical contact 170 from the fixedelectrical contact 168 in response to an abnormal electrical condition,such as a short circuit, overcurrent, or other abnormal voltage levelconditions. Electrical connectors formed in an example shown in FIG. 4as primary circuit contacts 220 a are carried within the interiorcompartment 128 of the switchgear frame 124 forming the housing, and thecircuit breaker 250 includes upper and lower terminals formed as contactarms 274,276 that engage the electrical connectors as the primarycircuit contacts when the circuit breaker is in an electricallyconnected position as shown in FIG. 4 . It should be understood thatthis electrically connected position may also correspond to the contacttesting position 160. Of course, the contact testing position 160 may beother positions with the switchgear frame 124 and interior compartment128.

The circuit breaker drive mechanism 152 is mounted on the switchgearframe 124 and connected to the circuit breaker truck 150 and configuredto rack in the truck where the circuit breaker is in the electricallyconnected position as shown in FIG. 4 , and rack out the truck where thecircuit breaker is electrically disconnected. In these examples, thecircuit breaker housing 164 is formed as a vacuum chamber housing andthe fixed and movable electrical contacts 168,170 are sealed within thevacuum chamber housing.

As shown in FIG. 4 , the circuit breaker truck 150 is configured forlinear movement in the interior compartment 128. This circuit breakertruck 150 is supported for linear movement on the switchgear frame 124,in this example, movable on spaced, parallel side rails 230 with a siderail shown in the view of a portion of the interior compartment 128 atFIG. 4 , illustrating the far section side rail 230 mounted on theinterior inner side of the switchgear frame 124, and on which front andrear rollers 232 a, 232 b may be supported for translational rollingmovement along the side rails 230 of the switchgear frame 124.

A side rail 230 may be mounted on each interior side of the switchgearframe 124 and positioned a few inches above any bottom floor sectionformed by the switchgear frame 124 and metal cladding. In the exampleshown in FIG. 4 , the circuit breaker drive mechanism 152 may be mountedon the bottom section of the switchgear frame 124 forming the switchgearhousing and connected to the truck 150, and configured to rack the truckand the circuit breaker 250 it carries into a first connected positionwhere the primary circuits 220 and secondary control or test circuits222 are electrically connected (FIG. 4 ), a circuit breaker testposition where primary circuits are electrically disconnected and thesecondary circuits are connected and a fully disconnected position whereboth primary and secondary circuits are disconnected.

The circuit breaker drive mechanism 152 may be configured to rack outthe truck 150 and the circuit breaker 250 into a second circuit breakertest position where the primary circuit 220 is electrically disconnectedand the secondary circuit 222 is connected to the secondary control ortest circuits. The electrically connected position as described may alsocorrespond to the electrical contact testing position 160. However,other locations may be used for the contact testing position 160.

Secondary connectors as part of the secondary circuit 222 may include acable or other secondary connection to connect and complete thesecondary circuit for testing and/or control. The drive mechanism 152may also be configured to rack out the truck 150 into a thirddisconnected position where the primary and secondary circuits 220,222are electrically disconnected. Further details of an example of thecircuit breaker drive mechanism 152 and other components are disclosedin U.S. patent application Ser. No. 17/422,540, filed Jul. 13, 2021, thedisclosure which is hereby incorporated by reference in its entirety.

The circuit breaker 250 as illustrated in FIG. 2 is a three-phasecircuit breaker and includes the first, second and third circuitbreakers 250 a, 250 b, 250 c each formed as a vacuum interrupter 270(FIG. 4 ) and defines the three poles 272 for the three-phase circuit asfirst, second and third single-phase circuits with the upper portion ofthe poles each having its contact arm 274 that connects to a bus barcircuit, for example, as part of an input as a power supply and theprimary circuit and the lower portion of the poles each having itscontact arm 276 having connectors to connect to a cable assembly orother electrical circuit as part of the output and connected to a load.

Although only one vacuum interrupter 270 and one pole 272 is illustratedin FIG. 4 , there are three vacuum interrupters 270 (FIG. 2 ) andassociated poles across the width of the circuit breaker truck 150. Eachvacuum interrupter 270 and pole 272 includes its upper contact arm 274and lower contact arm 276 and includes connectors that may include acontact finger assembly shown generally at 280 in FIG. 2 , which arereceived into primary circuit bushings 282 (FIG. 4 ) that are formed asa primary circuit housing to hold fixed primary circuit contacts 220 aas shown in the dashed lines, and which engage the contact fingerassemblies 280. The contact arms 274,276 may carry the contact fingerassemblies 280 (FIG. 2 ) formed as tulip contacts in differentconfigurations.

Each vacuum interrupter 270 operates as a switch and incorporates itsmovable electrical contact 170 and its fixed electrical contact 168 in avacuum as part of the breaker housing 164, in this example, formed as avacuum chamber housing. The separation of the electrical contacts168,170, such as during a short circuit or other abnormal electricalcondition, or even for electrical contact testing, results in a metalvapor arc, which is quickly extinguished. This medium-voltage switchgearsystem 100 includes the medium-voltage, three-phase vacuum circuitbreaker 250 having the three vacuum-interrupters 270. Each vacuuminterrupter 270 may provide the fixed electrical contact 168 and movableelectrical contact 170 in a flexible bellows to allow movement of themovable electrical contact in a hermetically-sealed ceramic with a highvacuum. The bellows may be made of stainless steel.

Vacuum interrupters may have a very long Mean Time to Failure (MTTF),and include high technology ceramic housings that impart a vacuumtightness with a resolution to the range of 10⁻⁷ hPa. The three-phasevacuum circuit breaker 250 as illustrated may operate with protectiverelays and other sensors to detect overcurrent or other abnormal orunacceptable conditions and signal the circuit breaker to switch open.

To maintain heat control in the circuit breaker 250, each pole 272 mayinclude an insulator 284 as illustrated in FIG. 4 . Protective relaysand sensors may be formed as current transformers and potentialtransformers and temperature or pressure instruments and other sensingdevices that may operate in the electrical switchgear environment. Thevacuum interrupters 270 may operate at 5 KV, 15 KV, 27 KV, and 37 KVcorresponding to the normal operating range of medium-voltage switchgearsystems 100.

Referring now to FIG. 6 , there is illustrated a testing system 290 forthe circuit breaker 250 allowing the erosion contact test to beconducted while the truck 150 carrying the circuit breaker is removedfrom the switchgear frame 124 and housing and placed on a test platformillustrated generally at 292. In this example, the test platform 292 maybe a rectangular or other geometrically shaped support platform thatsupports the truck 150 carrying the circuit breaker 250 in a contacttesting position 294 on the test platform. In this example, the testplatform 292 includes wheel chocks 296 or indentations formed in thetest platform that position the truck 150 properly in the contacttesting position 294 on the test platform. The sensor circuit 180 has aconfiguration similar to that shown in FIG. 3 and is mounted on the testplatform 292 such as in a depression or cut-out 297 and positioned suchthat when the truck 150 rests on the test platform and the wheelsengaged in the wheel chocks 296, the sensor circuit 180 is aligned withthe proper circuit breaker 250 in the contact testing position 296.

The sensor circuit 180 operates similar to the sensor circuit describedrelative to FIGS. 2-5 and acquires displacement data of the actuatorpiston 174 and breaker housing 164 when the movable electrical contact170 is moved between the open and closed positions. The test platform292 includes three sensor circuits for three circuit breakers with eachsensor circuit 180 having a first laser circuit 182 having the firstlaser 184 (L1) and first optical sensor 198 (D1) and second lasercircuit 200 having the second laser 202 (L2) and second optical sensor204 (D2) as described also with the sensor circuit 180 of FIGS. 2-5 . Inthe example of FIGS. 2 and 3 , a portion of the switchgear frame 124 isillustrated, but that section of the switchgear frame could correspondto a separate test platform 292 on which the truck 150 and mountedcircuit breaker 250 will rest on after the truck is removed from theswitchgear housing and placed on the test platform 292.

Referring again to FIG. 7 , there is illustrated the underside of thecircuit breaker 250 such as when positioned within a switchgear housingor on the test platform 292. This view shows various components asdescribed before and shows relative positions of different surfaces onwhich the first and second optical beams may be emitted to differentportions of the surfaces and reflected therefrom. The first referenceslabeled 184 a indicate possible surface locations on which the firstoptical beam from the first laser 184 may be directed and referenceslabeled 202 a correspond to possible surface locations in which thesecond optical beam from the second laser 202 may be directed.

Referring now to FIG. 8 , there is illustrated generally at 300 ahigh-level flowchart showing a method of operating a switchgear system100 for determining the electrical contact erosion of the electricalcontacts 168,170 within the circuit breaker 250. The process starts(Block 302) and a truck 150 carrying a circuit breaker 250 is positionedinto a circuit testing position 160 within the switchgear interiorcompartment 128 (Block 304). A contact erosion test is instituted bymoving the movable electrical contact 170 between open and closedpositions (Block 306). Displacement data is acquired at the actuatorpiston 174 and the breaker housing 164 from the first and second opticalbeams emitted from first and second laser circuits 182,200 (Block 308).The electrical contact erosion is determined within the circuit breaker250 from the displacement data (Block 310). The process ends (Block312).

Referring now to FIG. 9 , there is illustrated a high-level flowchartgenerally at 350 and showing a method of operating the testing system290 for the circuit breaker 250. The process starts (Block 352) and thetruck 150 carrying the circuit breaker 250 is removed from theswitchgear interior compartment 128, and the truck is positioned on thetest platform 292 in the circuit testing position 160 (Block 354). Thecontact erosion test is instituted by moving the movable electricalcontact 168 between open and closed positions (Block 356). Displacementdata is acquired from the actuator piston 174 and the breaker housing164 via the first and second laser circuits 182,200 (Block 358). Theelectrical contact erosion is determined within the circuit breaker 250from the displacement data (Block 360). The process ends (Block 362).

In an example, the actuator piston 174 may be connected to the driveassembly 176 and include a stored energy mechanism that may include theactuator spring 188 and the actuator block 190. The actuator piston 174and drive assembly 176 may include different stroke adjusters, levershafts, and link rods that work in conjunction with the actuator spring188 and actuator block 190. The actuator piston 174 and drive assembly176 may include one or more magnetic actuators and a manual openingmechanism. A servomechanism or electromagnetic system may be used tocompress the actuator spring 188 for stored energy.

It should also be understood that instead of an optical beam, it ispossible to use an acoustic signal. The first and second optical sensors198,204 may receive reflected light. In an example, they may operateusing a position sensing device (PSD), charged coupled device (CCD), orCMOS devices. Other non-contact sensors may be used.

It is possible for the switchgear system 100 as described to obtainsignal data during each arcing event for “real-time” data collectionassociated with the contact erosion status and/or expected service liferemaining on the contacts of each circuit breaker. It is possible toprovide dynamic evaluations and update in real-time the data to allowpreventive maintenance scheduling and service without disengaging thecircuit breaker 250 from an electrically connected position. As notedbefore, it is also possible to use an acoustic emitter and acousticsensor instead of an optical laser and sensor or detector. It is alsopossible to use ultrasound sources and detectors.

The controller 226 may trigger the first and second laser circuits182,200 and obtain signals corresponding to reflected light beams atsuccessive intervals, such as in response to a trigger signal from astart of the movable electrical contact closing into a closed position,and a trigger signal from a start of opening of the movable electricalcontact into an open position. These intervals can range from 50microseconds to as much as 1 millisecond and values in between. In anexample, the sensor circuits 180 can be movable along the sensor supportbar 214 to allow adjustment at the contact testing position 160 whenemployed in the switchgear system 100 or along the testing position 294on the test platform 292. Different adjustment mechanisms could be usedsuch us slidable members on the first and second laser circuits receivedin grooves or slots of the sensor support laser 214.

If an acoustic emitter and sensor are used, the distance may becalculated by measuring the time required for ultrasonic waves to besent and received based upon the speed of sound. An optical beam oracoustic waves may be emitted in a pulsed manner where displacement dataand time may be translated to velocity with the slope of the distanceversus a time curve. Different power sources for the first and secondlasers and any optical sensors may be incorporated within the system100.

Also, the different surfaces on which the optical beam may be directedand reflected may include a reflective coating, film or other adhesivelyattached reflective strips or patches that help in reflectivity anddirecting the optical beam or acoustic signal or other ultrasonic signalback to the respective optical sensor or other detector, such as shownin the reflective patch 184 b in FIG. 7 . Any optical beam may bescanned and the time may be measured using laser scanning techniques.Data acquisition intervals can vary from as little as 20 microseconds upto 3 microseconds with possible intermediate values. Travel curves canbe provided from the displacement data. It is possible to use cloudcomputing as part of the controller 226 or a large network controlcenter when there are many different circuit breakers and differentswitchgear frames and housings.

This application is related to copending patent application entitled,“SWITCHGEAR SYSTEM THAT DETERMINES CONTACT EROSION IN CIRCUIT BREAKER,”which is filed on the same date and by the same assignee and inventors,the disclosure which is hereby incorporated by reference.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims.

The invention claimed is:
 1. A testing system for a circuit breaker,comprising: a truck carrying a circuit breaker, wherein the circuitbreaker comprises, a breaker housing, a fixed electrical contact and amovable electrical contact mounted within the breaker housing, saidmovable electrical contact being movable between an open and closedposition relative to the fixed electrical contact, an actuator pistonconnected to the movable electrical contact and extending downward fromthe breaker housing and configured to connect to a drive assembly thatdrives the actuator piston and moves the movable electrical contactbetween open and closed positions with the fixed electrical contact; atest platform configured to support the truck carrying the circuitbreaker in a contact testing position on the test platform, wherein thetest platform comprises a sensor circuit mounted on the test platformand positioned under the truck and aligned with the circuit breaker whenthe truck is on the test platform in the contact testing position,wherein the sensor circuit is configured to acquire displacement data ofthe actuator piston when the movable electrical contact is moved betweenthe open and closed positions; and a controller coupled to the sensorcircuit and configured to receive the displacement data and determineelectrical contact erosion within the circuit breaker.
 2. The testingsystem of claim 1, wherein said sensor circuit comprises a first laserconfigured to emit a first optical beam onto a surface of the actuatorpiston, and a first optical sensor that receives reflected light fromthe surface of the actuator piston.
 3. The testing system of claim 2,wherein said sensor circuit further comprises a second laser configuredto emit a second optical beam onto a surface of the breaker housing, anda second optical sensor that receives reflected light from the surfaceof the breaker housing, and wherein said controller is configured todetermine actual electrical contact erosion based upon displacement ofthe actuator piston and breaker housing.
 4. The testing system of claim3, wherein said controller is configured to recalibrate the position ofthe fixed and movable electrical contacts based upon the displacementdata obtained from movement of the actuator piston and breaker housing.5. The testing system of claim 3, wherein said truck includes a bottompanel having orifices aligned with respective first and second lasers toallow the first and second optical beams from the first and secondlasers to pass upward through the bottom panel to surfaces of theactuator piston and breaker housing.
 6. The testing system of claim 3,wherein said controller is configured determine actual contact erosionby subtracting the displacement of the breaker housing from thedisplacement of the actuator piston.
 7. The testing system of claim 1,wherein first, second and third circuit breakers are carried on thetruck, and first, second and third sensor circuits are mounted on thetest platform underneath the truck and aligned with respective first,second and third circuit breakers when the circuit breaker is in thetesting position on the test platform.
 8. The testing system of claim 7,wherein said first, second and third circuit breakers are electricallyconnected in a three-phase circuit breaker configuration.
 9. The testingsystem of claim 1, wherein the movable electrical contact is moved openfrom the fixed electrical contact in response to an abnormal electricalcondition.
 10. The testing system of claim 1, wherein said circuitbreaker includes upper and lower terminals configured to engageelectrical connectors carried within an interior compartment of aswitchgear frame when the circuit breaker is in an electricallyconnected position.
 11. The testing system of claim 1, wherein saidactuator piston comprises a spring and cylindrically configured actuatorblock engaging the spring.
 12. The testing system of claim 1, whereinsaid breaker housing comprises a vacuum chamber housing and said fixedand movable electrical contacts are sealed within said vacuum chamberhousing.
 13. A testing system for a circuit breaker, comprising: a truckcarrying a circuit breaker, wherein said circuit breaker comprises, abreaker housing, a fixed electrical contact and a movable electricalcontact mounted within the breaker housing, said movable electricalcontact being movable between an open and closed position relative tothe fixed electrical contact, an actuator piston connected to themovable electrical contact and extending downward from the breakerhousing and configured to connect to a drive assembly that drives theactuator piston and moves the movable electrical contact between openand closed positions with the fixed electrical contact; a test platformconfigured to support the truck carrying the circuit breaker in acontact testing position on the test platform, wherein the test platformcomprises a first laser circuit mounted on the test platform andpositioned under the truck and aligned with the actuator piston of thecircuit breaker when the truck is on the test platform in the contacttesting position, and configured to emit a first optical beam andacquire displacement data of the actuator piston when the movableelectrical contact is moved between the open and closed positions; asecond laser circuit mounted on the test platform and positioned underthe truck and aligned with the breaker housing when the truck is on thetest platform in the contact testing position, and configured to emit asecond optical beam and acquire displacement data of the breaker housingwhen the movable electrical contact is moved between the open and closedpositions; and a controller coupled to the first and second lasercircuits and configured to receive the displacement data of the actuatorpiston and breaker housing and determine electrical contact erosionwithin the circuit breaker based upon displacement data of both theactuator piston and breaker housing.
 14. The testing system of claim 13,wherein said first laser circuit comprises a first optical sensor thatreceives reflected light from the surface of the actuator piston. 15.The testing system of claim 13, wherein said second laser circuitcomprises a second optical sensor that receives reflected light from thesurface of the breaker housing.
 16. The testing system of claim 13,wherein said controller is configured to recalibrate the position of thefixed and movable electrical contacts based upon the displacement dataobtained from movement of the actuator piston and breaker housing. 17.The testing system of claim 13, wherein said truck includes a bottompanel having orifices aligned with respective first and second lasers toallow the first and second optical beams from the first and second lasercircuits to pass upward through the bottom panel to respective surfacesof the actuator piston and breaker housing.
 18. The testing system ofclaim 13, wherein said controller is configured determine actual contacterosion by subtracting the displacement of the breaker housing from thedisplacement of the actuator piston.
 19. The testing system of claim 13,wherein first, second and third circuit breakers are carried on thetruck, and first, second and third sensor circuits, each comprisingfirst and second laser circuits, are mounted on the test platformunderneath the truck and aligned with respective first, second and thirdcircuit breakers when the truck is in the contact testing position. 20.The testing system of claim 19, wherein said first, second and thirdcircuit breakers are electrically connected in a three-phase circuitbreaker configuration.
 21. The switchgear system of claim 13, whereinsaid actuator piston comprises a spring and cylindrically configuredactuator block engaging the spring.
 22. The switchgear system of claim13, wherein said breaker housing comprises a vacuum chamber housing andsaid fixed and movable electrical contacts are sealed within said vacuumchamber housing.
 23. The testing system of claim 13, wherein saidcircuit breaker includes upper and lower terminals configured to engageelectrical connectors carried within an interior compartment of aswitchgear frame when the circuit breaker is in an electricallyconnected position.
 24. A method of operating a testing system for acircuit breaker, comprising: positioning a truck carrying a circuitbreaker into a contact testing position on a test platform, wherein thecircuit breaker comprises, a breaker housing, a fixed electrical contactand a movable electrical contact mounted within the breaker housing,said movable electrical contact being movable between an open and closedposition relative to the fixed electrical contact, an actuator pistonconnected to the movable electrical contact and extending downward fromthe breaker housing and configured to connect to a drive assemblycoupled to the actuator piston that drives the actuator piston and movesthe movable electrical contact between open and closed positions withthe fixed electrical contact; acquiring displacement data of theactuator piston when the movable electrical contact is moved between theopen and closed positions using a sensor circuit mounted on the testplatform and positioned under the truck and aligned with the circuitbreaker when the truck is in the contact testing position; and receivingthe displacement data within a controller coupled to the sensor circuitand determining electrical contact erosion within the circuit breaker.25. The method of claim 24, wherein the sensor circuit comprises a firstlaser configured to emit a first optical beam onto a surface of theactuator piston, and a first optical sensor that receives reflectedlight from the surface of the actuator piston.
 26. The method of claim24, wherein the sensor circuit further comprises a second laserconfigured to emit a second optical beam onto a surface of the breakerhousing, and a second optical sensor that receives reflected light fromthe surface of the breaker housing, and wherein said controller isconfigured to determine actual electrical contact erosion based upondisplacement of the actuator piston and breaker housing.
 27. The methodof claim 24, wherein the controller is configured to recalibrate theposition of the fixed and movable electrical contacts based upon thedisplacement data obtained from movement of the actuator piston andbreaker housing.
 28. A testing system for a circuit breaker, comprising:a test platform configured to support a truck carrying a circuit breakerin a contact testing position on the test platform, wherein the circuitbreaker comprises, a breaker housing, a fixed electrical contact and amovable electrical contact mounted within the breaker housing, saidmovable electrical contact being movable between an open and closedposition relative to the fixed electrical contact, an actuator pistonconnected to the movable electrical contact and extending downward fromthe breaker housing and configured to connect to a drive assembly thatdrives the actuator piston and moves the movable electrical contactbetween open and closed positions with the fixed electrical contact; asensor circuit mounted on the test platform and positioned under thetruck and aligned with the circuit breaker when the truck is on the testplatform in the contact testing position, wherein the sensor circuit isconfigured to acquire displacement data of the actuator piston when themovable electrical contact is moved between the open and closedpositions; and a controller coupled to the sensor circuit and configuredto receive the displacement data and determine electrical contacterosion within the circuit breaker.
 29. The testing system of claim 28,wherein said sensor circuit comprises a first laser configured to emit afirst optical beam onto a surface of the actuator piston, and a firstoptical sensor that receives reflected light from the surface of theactuator piston.
 30. The testing system of claim 29, wherein said sensorcircuit further comprises a second laser configured to emit a secondoptical beam onto a surface of the breaker housing, and a second opticalsensor that receives reflected light from the surface of the breakerhousing, and wherein said controller is configured to determine actualelectrical contact erosion based upon displacement of the actuatorpiston and breaker housing.
 31. The testing system of claim 30, whereinsaid controller is configured to recalibrate the position of the fixedand movable electrical contacts based upon the displacement dataobtained from movement of the actuator piston and breaker housing. 32.The testing system of claim 30, wherein said controller is configureddetermine actual contact erosion by subtracting the displacement of thebreaker housing from the displacement of the actuator piston.